SliverFillViewport constructor

const SliverFillViewport({Key key, @required SliverChildDelegate delegate, double viewportFraction: 1.0 })

Creates a sliver whose box children that each fill the viewport.

Implementation 

const SliverFillViewport({
  Key key,
  @required SliverChildDelegate delegate,
  this.viewportFraction = 1.0,
}) : assert(viewportFraction != null),
     assert(viewportFraction > 0.0),
     super(key: key, delegate: delegate);